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*UNITED STATES PATENT onnrcn TJEU H.,BA .EKEI|AND, 0F YONKERS, NEW YORK,ASSIGNOR TO GENERAI BAKELITE COMPANY, OF NEW YORK, N. Y., A CORPORATIONOF NEW YORK.

"rnnn'rmu rune-01L AND conrmc on. mrnn'anarme owners THEREWITIL lfilfifit No Drawing. I

To all whom it may concern:

' Be it known that l, LEO H. BArmnnANo, a citizen of the United States,residing at Yonkers, in the county of Westchesterand State of New York,have invented certain new and useful Improvements in Treating Tung ".0l1and Coating or llmpregnating ()bjects Therewith, of which the followingis a specification.

llt is known thatso-called tung oil or Chinese Wood oil polymeriz'es orsolidifies under the continued action of sufficiently high temperatures.Thus, ordinary tung. oil Wlll elatinize and solidify in time at about232 b. This solidification is independent of any process of oxidationdue to j atmospheric oxygen, and is therefore quite distinct from thehardening process induced in linseed oil, or in other so-called"dryingoils, in which the solidification is due.to oxidation Solidified tungoil is an excellent electrical insulator, and has furthermore theadvantage that it does not melt when subjected to higher temperatures.In this respect it is qulte different from the resinous substances whichhave been used heretofore in the electrical art for impregnating coils'of this material for impregnation difiicult hill or impracticable, forthe reason that at the high temperatures at which solidification occursrapidl organic materials and certain other substances are liable todamage or destruction through the action of the heat. This applies tosuch materials as contain fabric or fiber,- paper, soft solder, enamel,etc., which are commonly used in the construction of electricaldevices.Furthermore, the application of these high temperatures is by no meanseasy, involving many technical difficulties and .com lications. It hasbeen asserted that the lntroduction of certain substances, for examplemetallic salts, reduces the temperature at which solidification occurs;but the introduction of such substances constitutes an element of dangerfor electrical purposes, particularly where very high voltages are to beused.

' The present invention comprises a' process Specification of LettersPatent.

I Application filed January 16, 1917. Serial No. 142,693:

whereby'the gelatinization or solidification of the tungoil may becarried out ata relatively low temperature, and may be accomplished witheasily available means, for eitample steam and ordinary apparatus heatedby steam. ll base my process on the fact that tung oil, by a preliminaryheating at relatively high temperatures followed by coolmg, acqulres theproperty of gelatmizing rapidly at temperatures materially below thoseof the initial heating. 'Tung oil which has been subjected to suchpreliminary treatment can, it is found, be stored and kept in stock forlong eriods, not only at ordinary temperatures, ut at temperatures'ashigh as 80 or even 100 C. lln certain instances the treated oil has beenkept for more than a month at 100 C. without gelatinizingg and at 75 to80 C. it appears to keep indefinitely, except for some oxidation fromthe surface downward when exposed to the air. The above facts are ofgreat technical importance when it is taken into considera tion that inthe impregnation of coils and other electrical devices the operation iscustomarily carried out in large tanks heated by steam jackets, theconditions being such as to render it impractical frequently or rapidlyto cool the contents, which are accordingly kept warm for long periods.

The invention comprises also the modified oil capable of solidificationat a rela? tively low temperature, and the process involvlng thecoating-or impregnation of objects with such modified oil.

l[ have found it essential for practical urposes that the treatment ofthe oil eading to its gelatinization or solidification should be carriedout in two distinct stages. The first stage is carried out at relativelyhigh temperatures while avoiding solidification. For this purpose theoil is preferably quickly heated to 205 to 210 6., and is heldapproximatel at this temperature for some two and onealf hours, withsufficient stirring to prevent it from burning on the bottom of the pot.After sufficient treatment, a

sample of the oil when cooled. should have about the consistence ofordinary molasses: A small scale test will indicate when this point isreached. As soon as the desired condition is attained the oil is quicklycooled;

. thinner.

by any appropriate means, and may be at once stored for further use. nowbe found to undergo gelatinization readily at temperatures approximatmg150 to 160 C. in eight or nine hours, while as stated above, it may bekept at temperatures as high as 80 or even 100 C. for several weekswithout material change. I However, in order to avoid alteration byoxidation from the surface, it is desirable to store the oil in tanksfree from oxygen or containing" an inert gas, as for instance flue gas,illuminating gas, carbon dioxid, nitrogen or hydrocarbons, therebyavoidin the formation by oxidation of a surface s in upon the liquid.-

The thickened tung oil, prepared as indicated above, can be used toexcellent advantage for impregnating or coating paper, fabrics, wood orthe like. For such purposes the ordinary methods of impregnation andcoating are readily available. Usually there is no necessity for theaddition of thinners or reducers, although it is'obvious that oils,resins or the like, may be added if desired. In certain cases theaddition of a lighter or more mobile tung oil is beneficial as a Thisprepared tung oil is also advantageously used in con unction withsuitable fillers or other substances for the preparation of moldingmixtures.

Electric coils or similar devices impregnated with tung oil, which isafterward gelatinized or polymerized, present the disadvantage that theydo not sufiiciently resisted the action of transformer oils and otherliquids used in transformers, such liquids exerting a solvent orswelling action on the polymerized tung oil. In order to avoid this suchdevices may be incased in suitable envelops which will prevent access ofthe liquid to the gelatinized tung oil. Any suitable material which isnot ma terially affected by the transformer oil or similar liquids, andwhich does not liquefy too readily under an increase of temperature, canbe used to advantage for this purpose. For example, transformer coilsimpregnated with polymerized tung oil, may be coated with a protectivelayer of a material consisting of or containing the known infusible andinsoluble phenohc condensation products; or the condensation product orother protective material, instead of being applied directly,may beembodied in or associated with a protectivelayer of fabric; or it may beused in conjunction with other suitable materials, as for example inertfillers or finely divided. substances.

While I have specified in the foregoing description certain definitetemperatures and times of treatment as constituting the 'mostadvantageous operating conditions known to me, it is to be understoodthat the invention The oil will ried out at temperatures somewhat lower.

than those specified as most desirable, sufficient time beinggiven forattaining the results desired in the respective cases. Caution should beused however in employing during the preliminary treatment, temperaturesmuch above 210 C., as there is danger that the reaction may pass beyondcontrol.

In order to utilize my invention for the manufacture of molded articlessuch as molded insulators and the like, suitable molding mixtures areprepared by intimatel mixing the prepared or preliminarily heated oilwith sultable fillers or finely-divided solid materials. Or if desiredthe filler may be added directly to the raw oil and the mixturesubjected to the preliminary heat treatment as described above; but ingeneral it is much simpler first to prepare the oil and then toincorporate the filler. The proportion of filler to oil ma vary througha rather wide range, accor ing to the character of the filler and thepurpose in view. In general, a mixture containing in the neighborhood of.70 parts of filler by weight to 30 parts of oil will be foundsuitable, although 80 parts of filler to 20 of oil may afford acceptablemolding mixtures for certain purposes.

Such molding mixtures can be pressed in molds or in any suitable devicesaccording to the well known methods. A simple method is to shape thecold or warm molding mixture by application of sufiicient pressure inthe mold, and then to subject the molded article to a further hardeningprocess in an oven or by equivalent means at a temperature of about170180 C. At this temperature, 20 to 24 hours will sufiice to producethe maximum hardness of which the mixture is capable. stood that eitherhigher or lower temperatures may be used, but I have found that at thetemperature indicated the molded articles show less tendency todistortion and the process may be comp eted within a reasonable time ina baking oven.

Among the suitable fillers clay, silex, asbestos, and wood fiber may bementioned as typical of many others, such ,fillers being used eitheralone or in admixture with each other, or in conjunction with pigmentsor dyes. For some purposes the addition of It will be under ieiaoaaasphaltum or asphaltum compounds, including the so-called bituminite,maybe of advantage. An illustrative molding mixture may contain Theingredients are mixed as intimately as possible, and the molding andsubsequent baking are performed as described above. 7

lln order to improve the surface of the molded articles, they may becoated with a suitable external protective layer, for example a coatingof asphaltum, or better, a protective enamel of a phenolic condensationproduct, preferably of the infusi'ble type, this enamelbeing convertedinto its infusible and insoluble state by application of heat, or ofheat and pressure, in accordance with the methods now well understood inthe art.

The method of molding herein described, and the molded product, areclaimed in my divisional application Serial No. 211,639, filed Jan. 12,1918.

I claim 1. As a new article of manufacture, modified tung oil,practically stable at temperatures up to 80l00 (1., but solidifyin r attemperatures substantially below 200 2. As a new article of manufacture,modified tung oil, practically stable at temperatures up to 80100 0.,but solidifying without substantial evaporation at temperaturessubstantially below 200 C.

3. As a new article of manufacture, modified tung oil, practicallystable at temperatures up to 80-100 (l, but solidifying at a'loout150-160 C.

temperature while avoiding solidi cation thereof, and thereaftersolidifying the oil by application of heat at a temperature below thatof the initial heating.

6. A method of treating tung oil, consisting in heating the oil to atemperture of approximately 200 C. while avoiding solidificationthereof, and thereafter solidifying the oil at a temperatureapproximating USO-160 C.

7. A method of treating tung oil and impregnatingor coating objectstherewith, consisting in heating the oil to a relatively hightemperature while avoiding solidification thereof, and thereaftersolidifying the oil by application of heat in presence of the object tobe coated or impregnated, at a temperature below that of the initialheating.

8. A method of treating tung oil and impregnating or coating objectstherewith, consisting in heating the oil to a temperature ofapproximately 200 C. while avoid ing solidification thereof, andthereafter solidifying the oil by application of heat in presence of theobject to be coated or impregnated, at a materially lower temperature.

9. A method of treating tung oil and impregnating or coating objectstherewith, consisting in heating the oil to a tempera ture ofapproximately 200 C. while avoiding solidification thereof, andthereafter solidifying the oil in presence of the object to be coated orimpregnated, at approximately 150-160 C.

10. An article coated or impregnated with solidified tung oil, andprovided with an external coating resistant to transformer oil andordinary solvents.

11. An article coated or impregnated with solidified tung oil, andprovided with an external coating of an infusible and insoluble phenoliccondensation product.

In testimony whereof I aflix my signature in presence of two witnesses.

. LEO H. BAEKELAN D.

'Witnesses:

ALBERT lDUBIEL, Manna EVANS,

